The 4 one minute sprints twice a week is not, that I know, of a recommended form of exercise. The researchers were interested in the minimum amount of exercise out of scientific curiosity.
As you can imagine they experimented with other schedules less than and greater than 4 min x 2 time per week. Blood sugar was under excellent control with the minimum stated.
Strength, flexibility, co-ordination, fat loss, etc. are other considerations: but they did demonstrate their hypothesis that you need to deplete energy from your muscles to make room to sop up glucose in the blood.
p.s., you can imagine the horror we will soon face on late night TV as an infomercial selling a cheap exercise bike promises you CONTROL DIABETES AND LOSE WEIGHT WITH 8 MINUTES EXERCISE A WEEK. NO MONEY DOWN, PAY IN 8 EASY INSTALLMENTS, IF YOU ORDER NOW YOU GET A FREE ABERCISER. ORDER NOW OPERATORS ARE STANDING BY
Yes. If you are addicted to caffeine, although a large amount of caffeine will keep you awake, a small amount can promote sleep.
Despite my claim to never drink tea or coffee after 4 p.m. I occasionally take a 1/4 cup of tea before bed if I need to get to sleep quickly because I'll be rising early.
This is in proportion to how much tea/coffee I drink during the day: 2 or rarely 3 cups. I've known 6 cup a day coffee drinkers to drink an entire cup of coffee before bed. (I've also known them to have anxiety, shaky hands, and logorrhea)
The minimum amount of exercise was, interestingly enough, 4 one minute sprints on an exercise bicycle, all out, as hard as you can go with no holding back. You can take a break after each sprint for a short while to catch your breath. Do this twice a week.
The test subject and controls were from time to time given a glass of glucose water, and the experimenters measured how long it took to clear the sugar from the blood.
The theory was this. The muscles have a ready reserve of energy and resist taking more from the blood unless you deplete some of it. Experiments indicate that the benefits of this "minimum" exercise program last for weeks after ceasing it.
This is not my field and I could not tell you why sugar in the blood is bad for you, or why certain sugars are worse. However, I understand that the Berkley Wellness Letter and Science/Nature are evidence based publications. Anyone not credulous can spend about an afternoon looking these things up, though a library is probably better than the internet because many relevant publications are not free.
"The four building blocks of the universe are fire, water, gravel and vinyl." -- Dave Barry